Fluorinated neurokinin A antagonists

ABSTRACT

Peptide derivatives which are antagonists of neurokinin A. The derivatives have a modified peptide bond having a reduced amide and a fluorinated alkyl attached to the nitrogen atom of the modified peptide bond. For example, Asp-Ser-Phe-Val-Gly-LeuΨ[CH 2 N(CH 2 CF 3 )]Leu(NH 2 ).

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation, of application Ser. No. 08/282,3471 filed Jul. 29, 1994 ; which is a continuation of application Ser. No. 08/033,987 filed Mar. 19, 1993, now abandoned; which is a continuation of application Ser. No. 07/709,092 filed May 31, 1991, now abandoned; which is a Continuation-In-Part of application Ser. No. 07/686,593 filed Apr. 17, 1991, now abandoned; which is a Continuation-In-Part of application Ser. No. 07/356,031 filed May 23, 1989, ncw abandoned; which is a Continuation-In-Part of application Ser. No. 07/315,202, filed Feb. 24, 1989, now abandoned which is a continuation of Application Ser. No. 07/208,926, filed Jun. 20, 1988, now abandoned; which is herein incorporated by reference.

FIELD OF THE INVENTION

This invention relates to novel peptide derivatives which are antagonists of neurokinin A.

SUMMARY OF THE INVENTION The present invention comprises a peptide derivative of formula I:

X-A₁-A₂-A₃-A₄-A₅-A₆-A₇   I

wherein X is Y or YT.

Y is hydrogen, an alkyl of from 1-6 carbons, an acyl group of from 2-10 carbon atoms, or B₁ and B₂, wherein B₁ and B₂ are each independently selected from the group consisting of an alkyl of from 1-6 carbons or an acyl group of from 2-10 carbon atoms, with the proviso that only one of B₁ or B₂ is the acyl group. T is selected from the group consisting of 1-3 amino acid residues;

A₁ is -Asp-, -Glu- or a bond;

A₂ is -Ser-, -Thr-, -Ala-, -Asp-, -Glu-, -Val-, Tyr or PyroGlu;

A₃ is -Trp-, -Phe-, -β-(Napthyl)Ala-, or -Tyr-;

A₄ is -Val-, -Leu-, -Ile- or Phe;

A₅ is -Gly-, -Ala-, -Trp- or β-Ala;

A₆ is -Val-, -Leu-, -Ile-, -Trp- or -Phe-; and

A₇ is a residue of an amino acid derivative selected from the group consisting of Methioninol, Methioninamide, Norleucinol, Norleucinamide, Leucinol, Leucinamide, Argininol, Argininamide, Phenylalaninol or Phenylalaninamide.

The peptide derivative of Formula I is further characterized by modifying one of the peptide bonds between the amino acid residues of A₁-A₂, A₂-A₃, A₃-A₄, A₄-A₅, A₅-A₆, or A₆-A₇ to a modified peptide bond of

wherein Q is CH₂CF₃, CH₂CHF₂, CH₂CH₂F, or CH₂CF₂CF₃; or a pharmaceutically acceptable salt of Formula I.

The compounds of Formula I are useful in treating subjects in need of therapy where antagonism of neurokinin A is beneficial.

DETAILED DESCRIPTION OF THE INVENTION

Neurokinin A is a naturally occurring peptide having the formula of His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met(NH₂)-SEQ ID NO:1. Neurokinin A is widely distributed within body tissues and has a variety of typically undesirable biological effects.

The present invention comprises a new class of neurokinin A antagonists useful for treating maladies associated with the release of neurokinin A in a subject. For example, the compounds of the present invention are useful as immunosuppressants, and for treating subjects with various conditions such as arthritis, asthma, urinary incontinence, pain, inflammation, gastrointestinal hypermotility, neuritis, neuralgia, and headache, including migrane. “Subject” as used herein means mammals such as humans, sheep, horses, cattle, pigs, dogs, cats, rats and mice.

The compounds of the present invention are peptide derivatives of formula I:

X-A₁-A₂-A₃-A₄-A₅-A₆-A₇   I

wherein:

X is

Y, wherein Y is hydrogen, an alkyl of from 1-6 carbons, an acyl group of from 2-10 carbon atoms, or B₁ and B₂, wherein B₁ and B₂ are each independently selected from the group consisting of an alkyl of from 1-6 carbons or an acyl group of from 2-10 carbon atoms, with the proviso that B₁ or B₂ are not simultaneously the acyl group, or

YT, wherein T is from 1 to 3 amino acid residues;

A₁ is -Asp-, -Glu- or a bond;

A₂ is -Ser-, -Thr-, -Ala-, -Asp-, -Glu-, -Val-, Tyr or PyroGlu;

A₃ is -Trp-, -Phe-, -β-(Napthyl)Ala-, or -Tyr-;

A₄ is -Val-, -Leu-, -Ile-, or Phe;

A₅ is -Gly-, -Ala-, -Trp- or β-Ala;

A₆ is -Val-, -Leu-, -Ile-, -Trp- or -Phe-; and

A₇ is a residue of an amino acid derivative selected from the group consisting of Methioninol, Methioninamide, Norleucinol, Norleucinamide, Leucinol, Leucinamide, Argininol, Argininamide, Phenylalaninol or Phenylalaninamide.

The peptide derivative of Formula I is further characterized by modifying at least one peptide bond (—CONH—) between the residues of A₁-A₂, when A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅, A₅-A₆, or A₆-A₇ to a modified peptide bond having the formula:

wherein Q is CH₂CF₃, CH₂CHF₂, CH₂CH₂F, or CH₂CF₂CF₃, or a pharmaceutically acceptable salt of Formula I.

The abbreviations and nomenclature used herein are described as follows:

Abbreviations Compounds  1) Ala Alanine  2) Asp Aspartic Acid  3) Glu Glutamic acid  4) Ile Isoleucine  5) Leu Leucine  6) Phe Phenylalanine  7) Ser Serine  8) Thr Threonine  9) Trp Tryptophan 10) Tyr Tyrosine 11) Val Valine 12) β-(Napthyl)Ala β-(Napthyl) Alanine 13) β-Ala β-Alanine 14) PyroGlu PyroGlutamic Acid The following are amide derivatives of amino acids where the hydroxyl group (—OH) of the terminal carboxyl group (—COOH) has been replaced by an amino group (—NH₂): 15) Met(NH₂) Methioninamide 16) Nle(NH₂) Norleucinamide 17) Leu(NH₂) Leucinamide 18) Arg(NH₂) Argininamide 19) Phe(NH₂) Phenylalaninamide The following are alcohol derivatives of amino acids where the terminal carboxyl group (—COOH) is replaced by (—CH₂OH). 20) Met(CH₂OH) Methioninol 21) Nle(CH₂OH) Norleucinol 22) Leu(CH₂OH) Leucinol 23) Arg(CH₂OH) Argininol 24) Phe(CH₂OH) Phenylalaninol

The term “amino acid” as used herein includes the naturally occurring amino acids as well as other “non-protein” α-amino acids commonly utilized by those in the peptide chemistry arts when preparing synthetic analogs of naturally occurring peptides. The naturally occurring amino acids are glycine, alanine, valine, leucine, isoleucine, serine, methionine, threonine, phenylalanine, tyrosine, tryptophan, cysteine, proline, histidine, aspartic acid, asparagine, glutamic acid, glutamine, arginine, ornithine, and lysine.

Examples of “non-protein” α-amino acids are norleucine, norvaline, alloisoleucine, homoarginine, thiaproline, dehydroproline, hydroxyproline, homoserine, cyclohexylglycine, α-amino-n-butyric acid, cyclohexylalanine, homophenylalanine, phenylalanines substituted at the ortho, meta, or para position of the phenyl moiety with one or two of the following, a (C₁-C₄) alkyl, (C₁-C₄) alkoxy, halogen, or nitro groups or substituted with a methylenedioxy group, β-2- and 3-thienylalanine, β-2- and 3-furanylalanine, β-2-, 3-, and 4-pyridylalanine, β-(benzothienyl-2- and 3-yl)alanine, 62 -(1- and 2-naphthyl)alanine, O-alkylated derivates of serine, threonine, or tyrosine, S-alkylated cysteine, the O-sulfate ester of tyrosine, 3,5-diiodo-tyrosine and the D-isomers of the naturally occurring amino acids.

The natural amino acids with the exception of glycine, contain a chiral carbon atom. Unless otherwise specifically indicated, the optically active amino acids used in accordance with the present invention may be either the D or the L configuration, the L configuration being preferred. As is customary, the structure of peptides written out herein is such that the amino terminal end is on the left side of the chain and the carboxy terminal end is on the right side of the chain.

When two or more amino acids combine to form a peptide, the elements of water are removed, and what remains of each amino acid is called a residue. “Residue” is therefore an amino acid that lacks a hydrogen atom of the terminal amino group, and/or lacks the hydroxyl group of the terminal carboxyl group. Using accepted terminology, a dash (-)in front of (indicating loss of a hydrogen) and/or after (indicating loss of the hydroxyl) a three letter code for an amino acid or amino acid derivative indicates a residue.

Referring to Formula I, the moiety “X” may be any atom or group of atoms that do not adversely effect the function of the compound as described herein. X can be Y, wherein Y is hydrogen, an alkyl of from 1-6 carbons or an acyl group of from 2-10 carbon atoms. An “alkyl of from 1-6 carbons” means straight, branched or cyclic alkyls such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isopentyl, sec-pentyl, cyclopentyl, hexyl, cyclohexyl, and isohexyl. An “acyl group of from 2 to 10 carbon atoms” means straight, branched, cyclic, saturated and unsaturated acyl groups having 1 or 2 carbonyl moieties per group, for example, acetyl, benzoyl, succinyl, maleyl, and glutaryl. Preferably, Y is hydrogen.

Alternatively, Y can be B₁ and B₂. Each of B₁ and B₂ in connected to the alpha amino of the amino terminal amino acid thereby replacing hydrogen atoms normally attached to the nitrogen atom of an amino acid. B₁ and B₂ are independently selected from a group consisting of an alkyl of from 1-6 carbons or an acyl group of from 2-10 carbon atoms as previously defined. It is preferred that B₁ and B₂ are not simultaneously the acyl group.

X can also be YT, wherein Y is as previously defined and T is a group of from 1 to 3 amino acid residues. T is connected to A₁, or when A₁ is a bond T can be connected to A₂. These amino acid residues are selected from residues which do not adversely effect the activity of the compound. Preferred amino acid residues for T are Thr-, Lys-Thr- and His-Lys-Thr-.

In accordance with the present invention, the amino terminal amino acid can be an amino acid as defined by T, A₁ or A₂. As previously described, T may or may not be present in the compounds of the present invention. A₁ is also optionally present in the compounds of the present invention since A₁ may be a bond. When T is not present and when A₁ is a bond, A₂ is the amino terminal amino acid to which Y is attached.

Formula I of the present invention is further characterized by at least one modified peptide bond between any of the amino acid residues described herein.

Preferably, the modified peptide bond is between one of A₁-A₂, when A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅, A₅-A₆, or A₆-A₇, wherein the typical peptide bond of —CONH— between two amino acids is replaced with a reduced amide of the formula

Using conventional methods of identification, this is characterized as

with the symbol “Ψ” designating a modified peptide bond. An example follows using the terminology as defined herein when X is hydrogen, A₁ is -Ala-, A₂ is -Ser-, A₃ is -Phe-, A₄ is -Val-, A₅ is -Gly-, A₆ is -Leu- and A₇ is Leucinamide, and the modified peptide bond is between A₆ and A₇ with Q as CH₂CF₃:

Asp-Ser-Phe-Val-Gly-LeuΨ(CH₂NCH₂CF₃)Leu(NH₂)—SEQ ID NO:2.

The modified peptide bond of the present invention is a reduced amide (—CH₂N—) with a fluorinated alkyl (Q) attached via the alkyl to the nitrogen atom of the reduced amide. Examples of some modified peptide bonds used in accordance with the present invention follow:

a) CH₂NCH₂CF₃,

b) CH₂NCH₂CHF₂,

c) CH₂NCH₂CH₂F, and

d) CH₂NCH₂CF₂CF₃.

Of the foregoing modified peptide bonds, CH₂NCH₂CF₃ designated as (a) above, where Q is —CH₂CF₃, is preferred.

The compound of the present invention comprises at least one modified peptide bond as defined herein. Preferably, only one of the modified peptide bonds is present in the compound of the present invention, and, more preferably, the modified peptide bond is between A₆ and A₇.

The peptide derivatives of formula I can form pharmaceutically acceptable salts with any non-toxic, organic or inorganic acid. Illustrative inorganic acids which form suitable salts include hydrochloric, hydrobromic, sulphuric and phosphoric acid and acid metal salts such as sodium monohydrogen orthophosphate and potassium hydrogen sulfate. Illustrative organic acids which form suitable salts include the mono, di and tricarboxylic acids. Illustrative of such acids are, for example, acetic, glycolic, lactic, pyruvic, malonic, succinic, glutaric, fumaric, malic, tartaric, citric, ascorbic, maleic, hydroxymaleic, benzoic, hydroxybenzoic, phenylacetic, cinnamic, salicylic, 2-phenoxybenzoic and sulfonic acids such as methane sulfonic acid and 2-hydroxyethane sulfonic acid.

The compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CONH₂ group, the reduced amide bond substitution represented by —-Ψ[CH₂-N(Q)] is located between amino acid residues of A₆-A₇ and X is hydrogen can be prepared by techniques and procedures well known and appreciated by one of ordinary skill in the art. General synthetic procedures for preparing these compounds is set forth in Scheme A. In Scheme A, all substituents unless otherwise indicated are as previously defined.

Scheme A

STEP A:

The appropriate Boc-A₆ amino acid of structure (1) is coupled with the appropriate A₇ amino acid methyl ester of structure (2) to give the corresponding Boc-A₆-A₇ peptide methyl ester of structure (3).

For example, the appropriate Boc-A₆ amino acid of structure (1) is contacted with an equimolar amount of an appropriate A₇ amino acid methyl ester hydrochloride salt of structure (2), an equimolar amount of a coupling agent such as a mixture of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 1-hydroxybenzotriazole hydrate and a equimolar amount of a suitable non-nucleophilic amine such as diisopropylethylamine. The reactants are typically contacted in a suitable aprotic organic solvent such as methylene chloride or tetrahydrofuran. The reactants are typically stirred together at room temperature under a nitrogen atmosphere for 2-24 hours. The Boc-A₆-A₇ peptide methyl ester of structure (3) is recovered from the reaction zone by extractive methods known in the art. It may be purified by chromatography.

The selection of an appropriate coupling reagent is within the skill of the art. A particularly suitable coupling reagent where the amino acid to be added is Asp is N,N′-diisopropylcarbodiimide and 1-hydroxy-benzotriazole. The use of these reagents prevents nitrile and lactam formation. Other coupling agents are (1) carbodiimides (e.g., N,N-dicyclohexylcarbodiimide; (2) cyanamides (e.g., N,N-dibenzylcyanamide); (3) ketenimines; (4) isoxazolium salts (e.g., N-ethyl-5-phenyl-isoxazolium-3′-sulfonate; (5) monocyclic nitrogen containing heterocyclic amides of aromatic character containing one through four nitrogens in the ring such as imidazolides, pyrazolides, and 1,2,4-triazolides. Specific heterocyclic amides that are useful include N,N′-carbonyldiimidazole and N,N-carbonyl-di-1,2,4-triazole; (6) alkoxylated acetylene (e.g., ethoxyacetylene); (7) reagents which form a mixed anhydride with the carboxyl moiety of the amino acid (e.g., ethylchloroformate and isobutylchloroformate) or the symmetrical anhydride of the amino acid to be coupled (e.g., Boc-Phe-O-Phe-Boc) and (8) nitrogen containing heterocyclic compounds having a hydroxy group on one ring nitrogen (e.g., N-hydroxyphthalimide, N-hydroxysuccinimide and 1-hydroxy-benzotriazole). Other activating reagents and their use in peptide coupling are described by Kapoor, J. Pharm. Sci., 59 1-27 1970, which is incorporated herein by reference.

STEP B:

The amide functionality of the appropriate Boc-A₆-A₇ peptide methyl ester of structure (3) is thioamidated to give the corresponding Boc-A₆-Ψ[C(S)-NH]-A₇ peptide methyl ester of structure (4).

For example, the appropriate Boc-A₆-A₇ peptide methyl ester of structure (3) is contacted with a equimolar amount of an appropriate thioamidating reagent such as 2,4-bis(phenylthio)-1,3-dithio-2.4-diphosphetane-2,4-dithione. The reactants are typically contacted in a suitable aprotic organic solvent such as anhydrous tetrahydrofuran. The reactants are typically stirred together at room temperature under a nitrogen atmosphere for a period of time ranging from 2-24 hours. The Boc-A₆-Ψ[C(S)-NH]-A₇ peptide methyl ester of structure (4) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

STEP C:

The thioamide functionality of the appropriate Boc-A6-Ψ[C(S)-NH]-A₇ peptide methyl ester of structure (4) is reduced to give the corresponding Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5).

For example, the appropriate Boc-A₆-Ψ[C(S)-NH]-A₇ peptide methyl ester of structure (4) is contacted with a molar excess of a suitable reducing agent such as a mixture of nickel chloride hexahydrate (NiCl₂•6H₂O) and sodium borohydride. The reactants are typically contacted in a suitable organic solvent such as a mixture of tetrahydrofuran and methanol. The reactants are typically stirred together for a period of time ranging from 5 minutes to 5 hours and at a temperature range of from −10° C. to room temperature. The Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5) is recovered from the reaction zone by filtration and evaporation of the solvent. It may be purified by chromatography.

STEP D:

The amino functionality of the appropriate Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5) is functionalizde to give the corrsponding Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide methyl ester of structure (6).

For example, when the desired amino functionality is 2,2,2-trifluoroethyl, the appropriate Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5) is contacted with a molar excess of an appropriate alkylating agent such as 2,2,2-trifluoroethyl trifluoromethanesulfonate and an appropriate non-nucleophilic base such as triethylamine. The reactants are typically contacted in a suitable aprotic organic solvent such as benzene. The reactants are typically stirred together for a period of time ranging from 5 hours to 10 days at a temperature range of from room temperature to ref lux. The Boc-A₆-Ψ[CH₂-N(CH₂CF₃)]-A₇ peptide methyl ester of structure (6) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

Alternatively, when the desired amino functionality is 2,2-difluoroethyl, the appropriate Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5) is contacted with a molar excess of an appropriate alkylating agent such as 2,2-difluoroethyl trifluoromethanesulfonate and an appropriate non-nucleophilic base such as triethylamine. The reactants are typically contacted in a suitable aprotic organic solvent such as benzene. The reactants are typically stirred together for a period of time ranging from 5 hours to 10 days at a temperature range of from room temperature to reflux. The Boc-A₆-Ψ[CH₂-N(CH₂CHF₂)]-A₇ peptide methyl ester of structure (6) is recovered from the reaction zone by extractive methods known in the art. It may be purified by chromatography.

Alternatively, when the desired amino functionality is 2-fluoroethyl, the appropriate Boc-A₆-Ψ[CH₂-NH]-A₇ peptide methyl ester of structure (5) is contacted with a molar excess of an appropriate alkylating agent such as 2-fluoroethyl p-toluenesulfonate and an appropriate non-nucleophilic base such as triethylamine. The reactants are typically contacted in a suitable aprotic organic solvent such as benzene. The reactants are typically stirred together for a period of time ranging from 5 hours to 10 days at a temperature range of from room temperature to reflux. The Boc-A₆-Ψ[CH₂-N(CH₂CH₂F)]-A₇ peptide methyl ester of structure (6) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

Alternatively, when the desired amino functionality is 3,3,3-trifluoro-2,2-difluoropropyl, the appropriate Boc-A₆-Ψ[(CH₂-NH]-A₇ peptide methyl ester of structure (5) is contacted with a molar excess of an appropriate alkylating agent such as 3,3,3-trifluoro-2,2-difluorpropyl trichloromethanesulfonate and an appropriate non-nucleophilic base such as triethylamine. The reactants are typically contacted in a suitable aprotic organic solvent such as benzene. The reactants are typically stirred together for a period of time ranging from 5 hours to 10 days at a temperature range of from room temperature to reflux, The Boc-A₆-Ψ[CH₂-N(CH₂CF₂CF₃)]-A₇ peptide methyl ester of structure (6) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

STEP E:

The methyl ester functionality of the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide methyl ester of structure (6) is hydrolyzed to give the corresponding Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide of structure (7).

For example, the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide methyl ester of structure (6) is contacted with a molar excess of an appropriate base such as aqueous sodium hydroxide. The reactants are typically contacted in a suitable protic solvent such as ethanol. The reactants are typically stirred together at room temperature for a period of time ranging from 2-24 hours. The Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide of structure (7) is recovered from the reaction zone by acidification followed by extractive methods as is known in the art. It may be purified by chromatography.

STEP F:

The carboxylic acid functionality of the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide of structure (7) is amidated to give the corresponding Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (8).

For example, the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide of structure (7) is contacted with an equimolar amount of an activating agent such as isobutylchloroformate, an equimolar amount of an appropriate non-nucleophilic amine such as triethylamine and an excess amount of ammonia. The reactants are typically contacted in a suitable organic solvent such as ethyl acetate. The reactants are typically stirred together for a period of time ranging from 2-24 hours and at a temperature range of from −20° C. to room temperature. The Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (8) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

STEP G:

The Boc protecting group of the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (8) is hydrolyzed to give the corresponding A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9).

For example, the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (8) is contacted with a suitable acid, such as anhydrous hydrochloric acid or trifluoroacetic acid. The reactants are typically contacted in a suitable polar organic solvent such as dioxane. The reactants are typically stirred together at room temperature for a period of time ranging from 2-24 hours. The A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9) is recovered from the reaction zone by evaporation of the solvents. It may be purified by chromatography.

STEP H:

The appropriate A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9) is coupled to give the corresponding Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10).

For example, the appropriate A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9) can be coupled via a sequential condensation with the appropriate Boc-A₅ amino acid as described previously in step a, followed by removal of the Boc protecting group on the A₅ amino acid as described previously in step g. The resulting A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide may then be coupled with the appropriate Boc-A₄ amino acid, followed by removal of Boc protecting group on the A₄ amino acid. This procedure is repeated with the appropriate Boc-A₃ amino acid, the appropriate BoC-A₂ amino acid and ending with the appropriate Boc-A₁ amino acid to give the Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10).

Alternatively, the appropriate A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9) can be coupled via a fragment condensation with the appropriate preformed Boc-A₁-A₂-A₃-A₄-A₅ peptide to give the Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) as described previously in step a.

In addition, any combination of sequential and fragment condensations may be utilized for the coupling reaction in step h. For example, the appropriate A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (9) can be coupled via a fragment condensation with the appropriate preformed Boc-A₂-A₃-A₄-A₅ peptide to give the Boc-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide as described previously in step a. The Boc protecting group on the A₂ amino acid is then removed to give the A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide as described previously in step g. The A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide is then coupled with appropriate Boc-A₁ amino acid to give the Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) as described previously in step a.

The α-amino protecting group employed with each amino acid introduced into the polypeptide sequence may be any such protecting group known to the art. Among the classes of α-amino protecting groups contemplated are (1) acyl type protecting groups such as: formyl, trifluoroacetyl, phthalyl, toluenesulfonyl (tosyl), benzenesulfonyl, nitro-phenylsulfenyl, tritylsulfenyl, o-nitrophenoxyacetyl and α-chlorobutyryl; (2) aromatic urethane type protecting groups such as benzyloxycarbonyl and substituted benzyloxycarbonyl, such as p-chlorobenzyloxycarbonyl, p-nitrobenzyloxycarbonyl, p-bromobenzyloxycarbonyl, p-methoxybenzyloxycarbonyl, 1-(p-biphenylyl)-1-methylethoxy-carbonyl, α, α-dimethyl-3,5-dimethoxybenzyloxycarbonyl and benzhydryloxycarbonyl; (3) aliphatic urethane protecting groups such as tert-butyloxycarbonyl (Boc), diisopropyl-methoxycarbonyl, isopropyloxycarbonyl, ethoxycarbonyl and allyloxycarbonyl; (4) cycloalkyl urethane type protecting groups such as cyclopentyloxycarbonyl, adamantyloxycarbonyl and cyclohexyloxycarbonyl; (5) thio urethan type protecting groups such as phenylthiocarbonyl; (6) alkyl type protecting groups such as triphenylmethyl (trityl) and benzyl; and (7) trialkylsilane groups such as trimethylsilane. The preferred α-amino protecting group is tert-butyloxycarbonyl (Boc).

STEP I:

The Boc protecting group on A₁ and various other protecting groups on amino acids A₁-A₇ of the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q) ]-A₇ peptide amide of structure (10) are removed by methods well known in the art to give the corresponding A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (11).

For example, the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) may be subjected to a global deprotection using HF to give the corresponding fully deprotected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (11). Typically, the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) is dissolved in HF along with a suitable scavenger such as anisole. The reactants are typically stirred together at 0° C. for a period of time ranging from 20 minutes to 1 hour. The fully deprotected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (11) is recovered from the reaction zone by evaporation of the solvent. It may be purified by chromatography.

Starting materials for use in Scheme A are readily available to one of ordinary skill in the art. For example, 2,2,2-trifluoroethyl trifluoromethanesulfonate is described in J.Am. Chem. Soc. 77 6214 1955, 2,2-difluoroethyl trifluoromethanesulfonate and 2-fluoroethyl p-toluenesulfonate are described in J.Med.Chem. 23 985 1980 and 3,3,3-trifluoro-2,2-difluoropropyl trichloromethanesulfonate is described in J.Med.Chem. 16 1354 1973.

The following examples present typical syntheses as described in Scheme A. These examples are understood to be illustrative only and are not intended to limit the scope of the present invention in any way. As used herein, the following terms have the indicated meanings: “g” refers to grams; “mmol” refers to millimoles; “mL” refers to milliliters; “bp” refers to boiling point; “mp” refers to melting point; “° C.” refers to degrees Celsius; “mm Hg” refers to millimeters of mercury; “μL” refers to microliters; “μg” refers to micrograms; and “μM” refers to micromolar. The term “Boc” means t-butyloxycarbonyl, the term “β-Chxl” means β-cyclohexyl, the term “Bn” means benzyl, “OBn” means benzyloxy, and the term “Ac” means acetyl. The peptides prepared in the following examples are comprised of L-amino acid residues unless otherwise indicated.

EXAMPLE 1 Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) SEQ ID NO:2—MDL 102,409.

Step a: Boc-Leu-Leu(OMe)

Mix Boc-Leu hydrate (5.0 g, 20 mmol), Leu(OMe) hydrochloride (3.63 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate (25 mL), wash with cold 0.5 N hydrochloride acid, saturated aqueous sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent invacuo to give the title compound (5.83 g).

Step b: Boc-Leu-Ψ[C(S)-NH]Leu(OMe)

Mix Boc-Leu-Leu(OMe) (0.36 g, 1 mmol), 2,4-bis(phenylthio)-1,3-dithio-2.4-diphosphetane-2,4-dithione (0.45 g, 1.1 mmol) and anhydrous tetrahydrofuran (3 mL). Stir at room temperature under a nitrogen atmosphere for 8 hours. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent invacuo to give the title compound.

Step c: Boc-Leu-Ψ[CH₂-NH]Leu(OMe)

Dissolve Boc-Leu-Ψ[C(S)-NH]Leu(OMe) (1 mmol) in a mixture of 1:1 tetrahydrofuran/methanol (10 mL). Add nickel chloride hexahydrate (NiCl₂•6H₂O) (1.9 g, 8 mmol) and cool in an ice bath. Add sodium borohydride (0.91 g, 24 mmol) and stir at room temperature under a nitrogen atmosphere for 20 minutes. Filter and evaporate the solvent invacuo to give the title compound (0.14 g, 40.6%).

Step d: Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(OMe)

Mix Boc-Leu-Ψ[CH₂-NH]Leu(OMe) (0.15 g, 0.435 mmol), 2,2,2-trifluoroethyl trifluoromethanesulfonate (0.41 g, 1.74 mmol), trifluoroacetic acid (0.06 mL, 0.435 mmol) and benzene (2 mL). Heat at reflux for 7 days, occasionally adding additional 2,2,2-trifluoroethyl trifluoromethanesulfonate and trifluoroacetic acid. Cool to room temperature, wash with 1 N hydrochloric acid then saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent invacuo to give the title compound.

Step e: Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu

Dissolve Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(OMe) (0.45 g, 1.055 mmol) in ethanol (10 mL) and add 1 N sodium hydroxide (10 mL). Stir at room temperature overnight. Dilute with water and acidify with 1 N hydrochloric acid. Extract into ethyl acetate, dry (MgSO₄) and evaporate the solvent invacuo to give the title compound (0.40 g, 92%).

Step f: Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2)

Dissolve Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu (0.40 g, 0.97 mmol) in ethyl acetate (10 mL) and cool to −20° C. Add triethylamine (0.15 mL, 1 mmol) and isobutylchloroformate (0.13 mL, 1 mmol). Stir at −20° C. for 20 minutes. Bubble ammonia gas into the reaction mixture at −20° C. for 10 minutes then allow to warm to room temperature overnight. Wash with brine and dry (MgSO₄). Evaporate the solvent invacuo to give the title compound (0.88 g).

Step q: Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2)•hydrochloride

Mix Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2) (0.88 g) and 4 N hydrochloric acid in dioxane (10 mL). Stir under nitrogen atmosphere until the reaction is complete. Evaporate the solvent invacuoto give the title compound (0.49 g). 298E-168

Step h: Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) SEQ ID NO;3

Mix Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2)•hydrochloride (0.49 g, 1.57 mmol), Boc-Ser(OBn)-Phe-Val-Gly (0.94 g, 1.57 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (0.34 g, 1.73 mmol), 1-hydroxybenzotriazole hydrate (0.26 g, 1.73 mmol), diisopropylethylamine (0.3 g, 1.73 mmol) and methylene chloride (30 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Evaporate the solvent in vacuo to give Boc-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2) (0.84 g, 60%).

Mix Boc-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2) SEQ ID NO:4, (0.84 g, 0.943 mmol) and 4 N hydrochloric acid in dioxane. Stir at room temperature until the reaction is complete. Evaporate the solvent in vacuo to give Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃) ]Leu(NH2)•hydrochloride, SEQ ID NO:5, (0.92 g). Mix Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]Leu(NH2)•hydrochloride, SEQ ID NO:5, (829 mg, 1.0 mmol), Boc-Asp(OBn) (323 mg, 1.0 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (0.22 g, 1.1 mmol), 1-hydroxybenzotriazole hydrate (0.17 g, 1.1 mmol), diisopropylethylamine (0.29 g, 1.1. mmol) and methylene chloride (10 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Evaporate the solvent invacuo to give Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu (NH2), SEO ID NO: 3.

Step i: Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) SEQ ID NO:2.

Dissolve Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2), SEQ ID NO:3, (111 mg, 0.1 mmol) in hydrogen fluoride and anisole. Stir for 1 hour at 0° C. Allow the solvent to evaporate to give the title compound.

The following compounds can be prepared in a similar fashion to that described above in Example 1:

Asp-Ser-Phe-Val-β-Ala-Leu-Ψ[CH₂-N(CH₂CF₃) ]-Phe(NH₂) SEQ ID NO:6; and

pyroGlu-Phe-Phe-Gly-Leu-Ψ[CH₂-N(CH₂CF₃) ]-Nle (NH₂) SEQ ID NO:7.

The compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CONH₂ group, the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₆-A₇ and X is C₁-C₆ alkyl, C₂-C₁₀ acyl or 3 amino acid residues can be prepared by techniques and procedures well known and appreciated by one of ordinary skill in the art. General synthetic procedures for preparing these compounds are set forth in Scheme B. In Scheme B, all substituents unless otherwise indicated are as previously defined.

Scheme B

STEP A:

The Boc protecting group on A₁ of the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) or the Boc protecting group on A₂ of the appropriate Boc-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) is selectively removed by methods well known in the art to give the corresponding amino acid protected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) or A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12).

For example, the Boe protecting group on A₁ of the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) or the Boc protecting group on A₂ of the appropriate Boc-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (10) may then be removed to give the amino acid protected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) or the amino acid protected A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) as described previously in step g.

STEP B:

The A₁ amine terminus, when A₁ is not a bond, of the appropriate amino acid protected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) or the A₂ amine terminus of the appropriate amino acid protected A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) may be monoalkylated, dialkylated acylated, both alkylated and acylated or coupled with from 1-3 amino acid residues to give the corresponding amino acid protected mono-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding di-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected (C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) or the corresponding amino acid protected A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13).

For example, the appropriate amino acid protected A₁-A₂-A₃-A₄-A₅-A6-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) or the appropriate amino acid protected A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) is contacted with an equimolar amount of a suitable C₁-C₆ aldehyde, such as acetaldehyde and equimolar amount of a suitable reducing agent such as sodium cyanoborohydride. The reactants are typically contacted in a suitable organic solvent such as methanol. The reactantg are typically stirred together, maintaining a slightly acidic pH with dilute hydrochloride acid, for a period of time ranging from 2-24 hours and at a temperature range of from room temperature to reflux. The amino acid protected mono-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) and di-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ CH₂-N(Q))-A₇ peptide amide of structure (13) are recovered from the reaction zone by extractive methods as is known in the art. They may be separated and purified by chromatography.

Alternatively, the appropriate amino acid protected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) or the amino acid protected A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) is contacted with an equimolar amount of a suitable C₂-C₁₀ acylating agent, such as acetic anhydride or acetyl chloride and a molar excess of a suitable non-nucleophilic base such as triethylamine. The reactants are typically contacted in a suitable organic solvent such as methylene chloride or dimethylformamide. The reactants are typically stirred together for a period of time ranging from 2-24 hours and at a temperature range of from room temperature to reflux. The amino acid protected (C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

Alternatively, the appropriate mono-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) may be acylated to give the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) as described previously in Scheme B, step b.

Alternatively, the appropriate amino acid protected A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (12) is coupled with 1-3 amino acid residues using sequential condensation methods as is known in the art to give the corresponding amino acid protected A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) or the corresponding amino acid protected A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13).

In addition, the A₈ amine terminus of the appropriate amino acid protected A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) may be monoalkylated, dialkylated, acylated or both alkylated and acylated to give the corresponding amino acid protected mono-(C₁-C₆ alkyl)-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected di-(C₁-C₆ alkyl)-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected (C₂-C₁₀ acyl)-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) and the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) as described previously in Scheme B, step b.

In addition, the A₉ amine terminus of the appropriate amino acid protected A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) may be monoalkylated, dialkylated, acylated or both alkylated and acylated to give the corresponding amino acid protected Mono-(C₁-C₆ alkyl)-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13),the corresponding amino acid protected di-(C₁-C₆ alkyl)-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q) ]-A₇ peptide amide of structure (13), the corresponding amino acid protected (C₂-C₁₀ acyl)-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) and the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) as described previously in Scheme B, step b.

In addition, the A₁₀ amine terminus of the appropriate amino acid protected A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) may be monoalkylated, dialkylated, acylated or both alkylated and acylated to give the corresponding amino acid protected mono-(C_(l)-C₆ alkyl)-A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q) ]-A₇ peptide amide of structure (13),the corresponding amino acid protected di-(C₁-C₆ alkyl)-A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13), the corresponding amino acid protected (C₂-C₁₀ acyl)-A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇ peptide amide of structure (13) and the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q) ]-A₇ peptide amide of structure (13) as described previously in Scheme B, step b.

STEP C:

The various protecting groups on the amino acids residues on the compounds of Formula 1 described in Scheme B, step b may be removed by a global deprotection as described previously in Scheme A, step i.

Starting materials for use in Scheme B are readily available to one of ordinary skill in the art.

The following example presents a typical synthesis as described in Scheme S. This example is understood to be illustrative only an is not intended to limit the scope of the present invention in any way.

EXAMPLE 2 CH₃-C(O)-Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) SEQ ID NO:8.

Step a: Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH₂)•hydrochloride salt - SEQ ID NO:9.

Mix Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH₂) (1.09 g, 0.980 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent invacuo to give the title compound.

Step b: CH₃-C(O)-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-NH₂CF₃)]-Leu(NH₂) - SEQ ID NO: 10.

Dissolve Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2)•hydrochloride salt (2.30 g, 2.27 mmol) in dimethylformamide (15 mL) and treat with triethylamine (0.7 mL, 5 mmol) followed by acetic anhydride (0.2 mL, 2.27 mmol) and stir at room temperature overnight. Evaporate the solvent in vacuo, partition between methylene chloride and brine. Separate the organic phase, dry (MgSO₄), evaporate the solvent invacuo and purify by chromatography to give the title compound.

Step c: CH₃-C(O)-Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) - SEQ ID NO:8.

Dissolve CH₃-C(O)-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(NH2) (106 mg, 0.1 mmol) in hydrogen fluoride and anisole. Stir for 1 hour at 0° C. Allow the solvent to evaporate to give the title compound.

The following compounds can be prepared in a similar fashion to that described in Example 2:

Ac-Asp-Ser-Phe-Val-β-Ala-Leu-Ψ[CH₂-N(CH₂CF₃)]-Phe(NH₂) SEQ ID NO:11.

The compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CONH₂ group and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ can be prepared by teohniques and procedures well known and appreciated by one of ordinary skill in the art. General synthetic procedures for preparing these compounds is set forth in Scheme C. In Scheme C, all substituents unless otherwise indicated are as previously defined.

Scheme C provides a general synthetic procedure for preparing the compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CONH₂ and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆.

In step a, the appropriate Boc-A_(n) amino acid of structure (15), wherein n represents an integer 1-5, is coupled with an appropriate A_(n+1) amino acid methyl ester of structure (16), wherein n is as previously defined, to give the corresponding Boc-A_(n)-A_(n+1) peptide methyl ester of structure (17) as described previously in Scheme A, step a.

The selection of proper amino acid starting materials is based on the desired placement of the reduced amide bond in the final compound of Formula I. For example, if the reduced amide bond is to be located between amino acid residues A₃-A₄, the proper Boc-A_(n) amino acid of structure (15) would be one wherein n=3 and the proper A_(n+1) amino acid methyl ester of structure (16) would be one wherein n+1=4.

In step b, the amide functionality of the appropriate Boc-A_(n)-A_(n+1) peptize methyl ester of structure (17) is thioamidated to give the corresponding Boc-A_(n)-Ψ[C(S)-NH]-A_(n+1) peptide methyl ester of structure (18) as described previously in Scheme A, step b.

In step c, the thioamide functionality of the appropriate Boc-A_(n)-Ψ[C(S)-NH]-A_(n+1) peptide methyl ester of structure (18) is reduced to give the corresponding Boc-A_(n)-Ψ[CH₂-NH]-A_(n+1) peptide methyl ester of structure (19) as described previously in Scheme A, step c.

In step d, the amine functionality of the appropriate Boc-A_(n)-Ψ[CH₂-NH]-A_(n+1) peptide methyl ester of structure (19) is functionalized to give the corresponding Boc-A_(n)-Ψ[CH₂-N(Q)]-A₊₁ peptide methyl ester of structure (20) as described previously in Scheme A, step d.

In step e, the methyl ester functionality of the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide methyl ester of structure (20) is hydrolyzed to give the corresponding Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21) as described previously in Scheme A, step e.

In step f, the appropriate Boc-A₁-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21) is then coupled with the appropriate amino acids of peptides to give the corresponding Boc-protected compound of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ as described previously in Scheme A, step h.

For example, if the reduced amide bond is located between amino acid residues A₁ and A₂, wherein A₁ is not a bond, the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₁-Ψ[CH₂-N(Q)]-A₂, is coupled with an appropriately protected preformed A₃-A₄-A₅-A₆-A₇ peptide amide to give the corresponding Boc-A₁-Ψ[CH₂-N(Q)]-A₂-A₃-A₄-A₅-A₆-A₇ peptide amide.

If the reduced amide bond is located between amino acid residues A₂ and A₃, the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₂-Ψ[CH₂-N(Q)]-A₃, is coupled with an appropriately protected preformed A₄-A₅-A₆-A₇ peptide amide to give the corresponding Boc-A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇ peptide amide which is then optionally coupled with the appropriate Boc-A₁ amino acid, wherein A₁ is not a bond, give the corresponding Boc-A₁-A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇ peptide amide.

If the reduced amide bond is located between amino acid residues A₃ and A₄, the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₃-Ψ[CH₂-N(Q))-A₄, is coupled with an appropriately protected preformed A₅-A₆-A₇ peptide amide to give the corresponding Boc-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₂ amino acid to give the corresponding Boc-A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇ peptide amide which is then optionally coupled with the appropriate Boc-A₁ amino acid, wherein A₁ is not a bond, to give the corresponding Boc-A₁-A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₉-A₆-A₇ peptide amide.

If the reduced amide bond is located between amino acid residues A₄ and A₅, the appropriate Boc-A_(n)-Ψ[CH₂-N(Q) ]-A_(n+1) peptide of structure (21), as represented by Boc-A₄-Ψ[CH₂-N(Q))-A₅, is coupled with an appropriately protected preformed A₆-A₇ peptide amide to give the corresponding Boc-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₄ is then removed to give the corresponding A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₃ amino acid to give the corresponding Boc-A₃-A₄-Ψ[CH₂-N(Q) ]-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₂ amino acid to give the corresponding Boc-A₂-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇ peptide amide which is then optionally coupled with the appropriate Boc-A₁ amino acid, wherein A₁ is not a bond, to give the corresponding Boc-A₁-A₂-A₃-A₄-Ψ[CH₂-N(Q) ]-A₅-A₆-A₇ peptide amide.

If the reduced amide bond is located between amino acid residues A₅ and A₆, the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₅-Ψ[CH₂-N(Q)]-A₆, is coupled with an appropriately protected A₇ amino acid amide to give the corresponding Boc-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₅ is then removed to give the corresponding A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₄ amino acid to give the corresponding Boc-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₄ is then removed to give the corresponding A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₃ amino acid to give the corresponding Boc-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide which is then coupled with the appropriate Boc-A₂ amino acid to give the corresponding Boc-A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q) ]-A₆-A₇ peptide amide which is then optionally coupled with the appropriate Boc-A₁ amino acid, wherein A₁ is not a bond, to give the corresponding BoC-A₁-A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇ peptide amide.

If no further functionalization is desired, the protecting groups are removed from the various Boc-protected compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ to give the corresponding compound of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ as described previously in Scheme A, step i.

If further functionalization is desired, the A₁ amine terminus or the A₂ amine terminus of the appropriate compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ may be monoalkylated, dialkylated, acylated, both alkylated and acylated or coupled with 1-3 amino acid residues to give the corresponding amino acid protected mono-(C₁-C₆ alkyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding amino acid protected di-(C₁-C₆ alkyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding amino acid protected (C₂-C₁₀ acyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding A₁₀-A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding A₈ amine terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A_(2,) wherein A₁ is not a bond, A₂-A₃, A₃--A₄, A₄-A₅ or A₅-A₆, the corresponding A₉ amino terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding A₁₀ amino terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₁₀-A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ as described previously in Scheme B.

Starting materials for use in Scheme C are readily availiable to one of ordinary skill in the art.

The following examples present typical syntheses as described in Scheme C. These example are understood to be illustrative only and are not intended to limit the scope of the present invention in any way.

EXAMPLE 3 Asp-Ser-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met (NH₂) SEQ ID NO:12.

Step a.! Boc-Phe-Val(OCH₃)

Mix Boc-Phe (5.31 g, 20 mmol), Val(OMe) hydrochloride (3.36 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent invacuo to give the title compound.

Step b: Boc-PheΨ[C(S)-NH₂]-Val(OCH₃)

Mix Boc-Phe-Val(OCH₃) (378 mg, 1 mmol), 2,4-bis(phenylthio)-1,3-dithio-2,4-diphosphetane-2,4-dithione (0.45 g, 1,1 mmol) and anhydrous tetrahydrofuran (3 mL). Stir at room temperature under a nitrogen atmosphere for 8 hours. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent invacuo to give the title compound.

Step c: Boc-PheΨ[CH₂-NH₂]-Val(OCH₃)

Dissolve Boc-PheΨ[C(S)-NH₂]-Val(OCH₃) (394 mg, 1 mmol) in a mixture of 1:1 tetahydofuran/methanol (10 mL). Add nickel chloride hexahydrate (NiCl₂•6H₂O) (1.9 g, 8 mmol) and cool in an ice bath. Add sodium borohydride (0.91 g, 24 mmol) and stir at room temperature under a nitrogen atmosphere for 20 minutes. Filter and evaporate the solvent in vacuo to give the title compound.

Step d: Boc-PheΨ[CH₂-N(CH₂CF₂H)]-Val(OCH₃)

Mix Boc-PheΨ[CH₂-NH₂]-Val(OCH₃) (158 mg, 0.435 mmol), 2,2-difluoroethyl trifluoromethanesulfonate (372 mg, 1.74 mmol), triethylamine (0.06 mL, 0.435 mmol) and benzene (2 mL). Heat at reflux for 7 days, occasionally adding additional 2,2-difluoroethyl trifluoromethanesulfonate and triethylamine. Cool to room temperature, wash with 1 N hydrochloric acid then saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Step e: Boc-PheΨ[CH₂-N(CH₂CF₂H)]-Val

Dissolve Boc-PheΨ[CH₂-N(CH₂CF₂H)]-Val(OCH₃) (452 mg, 1.055 mmol) in ethanol (10 mL) and add 1 N sodium hydroxide (10 mL). Stir at room temperature overnight. Dilute with water and acidify with 1 N hydrochloric acid. Extract into ethyl acetate, dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Step f: Boc-Asp(O-β-Chxl)-Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂)—SEQ ID NO:13.

Mix Boc-Leu (4.98 g, 20 mmol), Met(OMe) hydrochloride (4.0 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Leu-Met(OMe).

Dissolve Boc-Leu-Met(OMe) (397 mg, 1.055 mmol) in ethanol (10 mL) and add 1 N sodium hydroxide (10 mL). Stir at room temperature overnight. Dilute with water and acidify with 1 N hydrochloric acid. Extract into ethyl acetate, dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Leu-Met.

Dissolve Boc-Leu-Met (351 mg, 0.97 mmol) in ethyl acetate (10 mL) and cool to −20° C. Add triethylamine (0.15 mL, 1 mmol) and isobutylchloroformate (0.13 mL, 1 mmol). Stir at −20° C. for 20 minutes. Bubble ammonia gas into the reaction mixture at −20° C. for 10 minutes then allow to warm to room temperature overnight. Wash with brine and dry (MgSO₄). Evaporate the solvent in vacuo to give Boc-Leu-Met(NH₂).

Mix Boc-Leu-Met(NH₂) (351 mg, 0.97 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give Leu-Met(NH₂) hydrochloride.

Mix Boc-Gly (3.5 g, 20 mmol), Leu-Met(NH₂) hydrochloride (5.98 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Cly-Leu-Met (NH₂).

Mix Boc-Gly-Leu-Met(NH₂) (1.09 g, 2.69 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give Gly-Leu-Met(NH₂) hydrochloride.

Mix Roc-PheΨ[CH₂-N(CH₂CF₂H)]-Val (7.58 g, 20 mmol), Gly-Leu-Met(NH₂) hydrochloride (7.12 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂)—SEQ ID NO:14.

Mix Boc-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Lau-Met (NH₂) SEQ ID NO:14, (1.09 g, 1.52 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give PheΨ[CH₂-N(CH₂CF₂H)]-Val-Cldy-Leu-Met(NH₂) hydrochloride.

Mix Boc-Ser(OBn) (5.9g, 20 mmol), PheΨ[CH₂-N(CH₂CF₂H) ]-Val-Gly-Leu-Met(NH₂) hydrochloride, SEQ ID NO:15, (13.04 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂) SEQ ID NO:16.

Mix Boc-Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂), SEQ ID NO:16, (1.09 g, 1.22 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂) hydrochloride, SEQ ID NO:17. Mix Boc-Asp(O-β-Chxl) (5.94 g, 20 mmol), Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂) hydrochloride, SEQ ID NO:17, (16.58 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Pier at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Scheme A, step i: Asp-Ser-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂)—SEQ ID NO:12.

Suspend Boc-Asp(O-β-Chxl)-Ser(OBn)-PheΨ[CH₂-N(CH₂CF₂H)]-Val-Gly-Leu-Met(NH₂), SEQ ID NO;13, (107 mg, 0.1 mmol) in hydrogen fluoride and anisoles Stir for 1 hour at 0° C. Allow the solvent to evaporate to give the title compound.

The following compounds can be prepared in a similar fashion to that described above in Example 3:

Asp-Ser-PheΨ[CH₂-N(CH₂CF₃)]-Val-Gly-Leu-Leu(NH₂)—SEQ ID NO:18;

Asp-Ser-PheΨ[CH₂-N(CH₂CF₃)]-Val-β-Ala-Leu-Phe(NH₂) - SEQ ID NO:19; and

pyroGlu-PheΨ[CH₂-N(CH₂CF₃)]-Phe-Gly-Leu-Met(NH₂)—SEQ ID NO:20.

The compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CH₂OH group and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₆-A₇ can be prepared by techniques and procedures well known and appreciated by one of ordinary skill in the art. General synthetic procedures for preparing these compounds are set forth in Scheme D. In Scheme D, all substituents unless otherwise indicated are as previously defined.

Scheme C provides a general synthetic procedure for preparing the compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CH₂OH and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₆-A₇.

In step a, the appropriate Boc-A₆-A₇ peptide methyl ester of structure (3) is reduced to give the corresponding Boc-A₆-[CH₂-NH]-A₇-Ψ[CH₂OH] peptide of structure (22).

For example, the appropriate Boc-A₆-A₇ peptide methyl ester of structure (3) is contacted with a molar excess of an appropriate reducing agent such as Red-A1. The reactants are typically contacted in a suitable aprotic organic solvent such as benzene. The reactants are typiCally stirred together for a period of time ranging from 5 minutes to 10 hours and at a temperature range of from room temperature to reflux. The Boc-A₆-Ψ[CH₂-NH]-A₇[CH₂OH] peptide of structure (22) is recovered from the reaction by acidification followed by extractive methods as is known in the art. It may be purified by chromatography.

In step b, the amino functionality of the appropriate Boc-A₆-Ψ[CH₂-NH]-A₇(CH₂OH] peptide of structure (22) is functionalized to give the corresponding Boc-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide of structure (23) as described previously in Scheme A, step d.

In step c, the Boc-protecting group on the A₆ amino acid residue of the appropriate Boc-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide of structure (23) is hydrolyzed to give the corresponding A₆-Ψ[CH₂-N(Q)]-A₇(CH₂OH] peptide of structure (24) as described previously in Scheme A, step g.

In step d, the A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide of structure (24) is coupled to give the corresponding Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)J-A₇[CH₂OH] peptide alcohol of structure (25) as described previously in Scheme A, step h.

If no further functionalizatiQn is desired, the Boc protecting group on A₁, wherein A₁ is not a bond, or the Boc protecting group on A₂ , wherein A₁ is a bond, and various other protecting groups on amino acids A₁-A₇, wherein A₁ is not a bond, or amino acids A₂-A₇, wherein A₁ is a bond, of the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of structure (25) are removed by methods well known in the art tQ give the corresponding A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, wherein A₁ is not a bond, the corresponding A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, wherein A₁ is a bond as described previously in Scheme A, step i.

If further functionalization is desired, the A₁ amine terminus, if A₁ is not a bond, or the A₂ amine terminus, if A₁ is a bond, of the appropriate Boc-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of structure (25) may be alkylated, dialkylated, acylated, both alkylated and acylated or coupled with 1-3 amino acid residues to give the corresponding amino acid protected mono-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇-Ψ[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected di-(C₁-C₆ alkyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q))-A₇[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected (C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇-Ψ[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, the corresponding amino acid protected A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇(CH₂OH] peptide alcohol of Formula I, the corresponding A₈ amine terminus alkylated, dialkylated, acylated, both alkylated and acylated amino acid protected A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I, the corresponding A₉ amine terminus alkylated, dialkylated, acylated, both alkylated and acylated amino acid protected A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q) ]-A₇[CH₂OH] peptide alcohol of Formula I or the corresponding A₁₀ amine terminus alkylated, dialkylated, acylated, both alkylated and acylated amino acid protected A₁₀-A₉-A₈-A₁-A₂-A₃-A₄-A₅-A₆-Ψ[CH₂-N(Q)]-A₇[CH₂OH] peptide alcohol of Formula I as described previously in Scheme B, step b. These compounds are then deprotected according to Scheme A, step i.

Starting materials for use in Scheme D are readily available to one of ordinary skill in the art.

The following examples present typical syntheses as described in Scheme D. These examples are understood to be illustrative only and are not intended to limit the scope of the present invention in any way.

EXAMPLE 4--MDL 100,988 Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH]•trifluoroacetate—SEQ ID NO:21.

Step a: Boc-Leu-Ψ[CH₂NH]-Leu[CH₂OH]

Dissolve Boc-Leu-Leu(OMe) (3.6 g, 10 mmol) in benzene (60 mL) and cool to 5° C. Add, by dropwise addition, Red-Al (20.5 mL of a 3.4 M solution in toluene, 70 mmol) and reflux for 10 minutes. Cool to room temperature, pour into ice-cold 0.5 M citric acid and adjust to pH 2.5 with citric acid. Wash with ether and adjust to pH 9 with saturated sodium hydrogen carbonate. Saturate with sodium chloride and extract with ethyl ether. Dry (MgSO₄), evaporate the solvent in vacuo and purify by silica gel chromatography (5% methyl/methylene chloride) to give the title compound (1.55 g, 49%).

Step b: Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu(CH₂OH]

Dissolve Boc-Leu-Ψ[CH₂NH]-Leu[CH₂OH] (0.49 g, 1.04 mmol) in anhydrous benzene (1 mL). Add 2,2,2-trifluoroethyl trifluoromethanesulfonate (0.11 g, 0.47 mmol) and stir under a nitrogen atmosphere at 60° C. overnight. Add additional 2,2,2-trifluoroethyl trifluoromethanesulfonate and triethylamine and reflux overnight. Cool to 0° C. and filter. Wash the filtrate with saturated sodium hydrogen carbonate, dry (MgSO₄) and evaporate the solvent in vacuo. Purify by silica gel chromatography (chloroform) to give the title compound (0.26 g, 43.5%).

Step c: Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH]•hydrochloride

Mix Boc-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH] (398 mg, 1 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 30 minutes. Evaporate the solvent in vacuo to give the title compound.

Step d: Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH]—SEQ ID NO:22.

Prepare Boc-Ser(OBn)-Phe-Val-Gly(OMe) by standard solution phase peptide synthesis.

Mix Boc-Ser(OBn)-Phe-Val-Gly(OMe), SEQ ID NO:23, (3.95 g, 6.45 mmol), 1 N sodium hydroxide (39 mL, 39 mmol), methanol (100 mL) and dioxane (60 mL). Stir at room temperature under a nitrogen atmosphere until hydrolysis is complete. Evaporate the solvent in vacuo and purify by silica gel chromatography (chloroform) to give Boc-Ser(OBn)-Phe-Val-Gly, SEQ ID NO:25, (3.32 g, 85.4%).

Mix Boc-Ser(OBn)-Phe-Val-Gly, SEQ ID NO:24, (0.6 g, 1.0 mmol), Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH] hydrochloride (0.3 g, 1.0 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (0.22 g, 1.1 mmol), 1-hydroxybenzotriazole hydrate (0.17 g, 1.1 mmol), diisopropylethylamine (0.29 g, 1.1 mmol) and methylene chloride (10 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH], SEQ ID NO:25 (0.65 g, 74%).

Mix Boc-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH], SEQ ID NO:25, (0.65 g, 0.74 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature under a nitrogen atmosphere until hydrolysis is complete. Evaporate the solvent in vacuo to give Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH] hydrochloride, SEQ ID NO:26, (0.66 g). Mix Boc-Asp(OBn) (0.26 g, 0.81 mmol), Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH] hydrochoride , SEQ ID NO:26, (0.66 g, 0.81 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (0.18 g, 0.89 mmol), 1-hydroxybenzotriazole hydrate (0.14 g, 0.89 mmol), diisopropylethylamine (0.23 g, 0.89 mmol) and dimethylformamide (8 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound (0.63 g).

Scheme At step i; Asp-Ser-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH]•trifluoroacetate—SEQ ID NO:21.

Dissolve Boc-Asp(OBn)-Ser(OBn)-Phe-Val-Gly-Leu-Ψ[CH₂-N(CH₂CF₃)]-Leu[CH₂OH] (0.63 g, 0.58 mmol) in hydrogen fluoride and anisole. Stir at 0° C. for 1 hour. Allow the solvent to evaporate to give the title compound following HPLC purification.

The following compounds can be prepared in a similar fashion to that described above in Example 4:

Asp-Ser-Phe-Val-⊖-Ala-LeuΨ[CH₂-N(CH₂CF₃)]-Phe[CH₂OH]—SEQ ID NO:27; and

pyroGlu-Phe-Phe-Gly-LeuΨ[CH₂-N(CH₂CF₃)]-Nle[CH₂OH]—SEQ ID NO:28.

The compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CH₂OH group and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ can be prepared by techniques and procedures well known and appreciated by one of ordinary skill in the art. General synthetic procedures for preparing these compounds are set forth in Scheme E. In Scheme E, all substituents unless otherwise indicated are as previously defined.

Scheme E provides a general synthetic procedure for preparing the compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CH₂OH and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆.

In step a, the methyl ester functionality of the appropriate Boc-A₇ amino acid methyl ester of structure (26) is reduced to give the corresponding Boc-A₇[CH₂OH] amino acid of structure (27) as described previously in Scheme C, step a.

In step b, the hydroxy functionality of the appropriate Boc-A₇Ψ[CH₂-OH] amino acid of structure (27) is protected as its benzyl ether to give the corresponding BOC-A₇[CH₂OBn] amino acid of structure (28).

For example, the appropriate Boc-A₇[CH₂OH] amino acid of structure (27) is contacted with an equimolar amount of benzyl chloride, an equimolar amount of a suitable base such as potassium carbonate and a catalytic amount of a alkylation catalyst, such as sodium iodide. The reactants are typically contacted in a suitable organic solvent such as acetone. The reactants are typically stirred together for a period of time ranging from 2-24 hours at a temperature range of from room temperature to reflux. The Boc-A₇[CH₂OBn] amino acid of structure (28) is recovered from the reaction zone by extractive methods as is known in the art. It may be purified by chromatography.

In step c, the Boc-protecting group on the A₇ amino acid of the appropriate Boc-A₇[CH₂OBn] amino acid of structure (28) is removed to give the corresponding A₇[CH₂OBn] amino acid of structure (29) as described previously in Scheme A, step g.

In step d, the appropriate A₇[CH₂OBn] amino acid of structure (29) is coupled to give the corresponding Boc-protected compounds of Formula I wherein A₇ is an amino acid residue as previously described wherein the —COOH group is replaced with a —CH₂OH and the reduced amide bond substitution represented by —Ψ[CH₂-N(Q)] is located between amino acid residues of A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ as described previously in Scheme A, step h.

For example, if the reduced amide bond is located between amino acid residues A₁ and A₂, wherein A₁ is not a bond, the appropriate A₇[CH₂OBn] amino acid of structure (29) is coupled with Boc-A₆ to give the corresponding Boc-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₆ is then removed to give the corresponding A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₅ to give the corresponding Boc-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₅ is then removed to give the corresponding A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₄ to give the corresponding Boc-A₄-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₄ is then removed to give the corresponding A₄-A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₃ to give the corresponding Boc-A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A1-Ψ[CH₂-N(Q)]-A₂, to give the corresponding Boc-A₁-Ψ[CH₂-N(Q)]-A₂-A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide of Formula I, wherein A₁ is not a bond.

If the reduced amide bond is located between amino acid residues A₂ and A₃, the appropriate A₄-A₅-A₆-A₇[CH₂OBn] peptide is coupled with the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₂-Ψ[CH₂-N(Q)]-A₃, to give the corresponding Boc-A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide which is then optionally coupled with the appropriate Boc-A₁, wherein A₁ in not a bond, to give the corresponding A₁-A₂-Ψ[CH₂-N(Q)]-A₃-A₄-A₅-A₆-A₇[CH₂OBn] peptide of Formula I.

If the reduced amide bond is located between amino acid residues A₃ and A₄, the appropriate A₅-A₆-A₇[CH₂OBn] peptide is coupled with the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₃-Ψ[CH₂-N(Q)]-A₄, to give the corresponding Boc-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₂ to give the corresponding Boc-A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇[CH₂OBn] peptide which is then optionally coupled with the appropriate Boc-A₁, wherein A₁ in not a bond, to give the corresponding Boc-A₁-A₂-A₃-Ψ[CH₂-N(Q)]-A₄-A₅-A₆-A₇[CH₂OBn] peptide of Formula I.

If the reduced amide bond is located between amino acid residues A₄ and A₅, the appropriate A₆-A₇[CH₂OBn] residue is coupled with the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₄-Ψ[CH₂-N(Q)]-A₅, to give the corresponding Boc-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₄ is then removed to give the corresponding A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₃ to give the corresponding Boc-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₂ to give the corresponding Boc-A₂-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide which is then optionally coupled with the appropriate Boc-A₁, wherein A₁ in not a bond, to give the corresponding Boc-A₁-A₂-A₃-A₄-Ψ[CH₂-N(Q)]-A₅-A₆-A₇[CH₂OBn] peptide of Formula I.

If the reduced amide bond is located between amino acid residues A₅ and A₆, the appropriate A₇[CH₂OBn] residue of structure (29) is coupled with the appropriate Boc-A_(n)-Ψ[CH₂-N(Q)]-A_(n+1) peptide of structure (21), as represented by Boc-A₅-Ψ[CH₂-N(Q)]-A₆, to give the corresponding Boc-A₅-Ψ[CH₂N(Q)]-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₅ is then removed to give the corresponding A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₄ to give the corresponding Boc-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₄ is then removed to give the corresponding A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₃ to give the corresponding Boc-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₃ is then removed to give the corresponding A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide which is then coupled with the appropriate Boc-A₂ to give the corresponding Boc-A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide. The Boc-protecting group on amino acid A₂ is then removed to give the corresponding A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide which is then optionally coupled with the appropriate Boc-A₁, wherein A₁ in not a bond, to give the corresponding Boc-A₁-A₂-A₃-A₄-A₅-Ψ[CH₂-N(Q)]-A₆-A₇[CH₂OBn] peptide of Formula I.

If no further functiqnalization is desired, the Boc protecting group on A₁, wherein A₁ is not a bond, and the Boc protecting group on A₂, wherein A₁ is a bond, the benzyl protecting group on A₇ and various other protecting groups on amino acids A₁-A₇, wherein A₁ is not a bond, and A₂-A₇, wherein A₁ is a bond, of the appropriate protected compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ are removed by methods well known in the art to give the corresponding compounds of Formula I wherein the reduced amide bond is loctated between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅--A₆ as described previously in Scheme A, step i.

If further functionalization is desired, the A₁ amine terminus, wherein A₁ is not a bond, or the A₂ amine terminus, wherein A₁ is a bond, of the appropriate protected compounds of Formula I wherein the reduced amide bond is loctated between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆ may be alkylated, dialkylated, acylated, both alkylated and acylated or coupled with 1-3 amino acid residues to give the corresponding amino acid protected mono-(C₁-C₆ alkyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding amino acid protected di-(C₁-C₆ alkyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂-A₃, A₃-A₄, A₄-A₅ or A₅-A₆, the corresponding amino acid protected (C₂-C₁₀ acyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein Al is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆, the corresponding amino acid protected (C₁-C₆ alkyl)-(C₂-C₁₀ acyl)-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆, the corresponding amino acid protected A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁-A₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅-A₆, the corresponding amino acid protected A₉-A₈compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆, the corresponding amino acid protected A₁₀-A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅-A₆, the corresponding A₈ amine terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆, the corresponding A₉ amine terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆, the corresponding A₁₀ amine terminus monoalkylated, dialkylated, acylated, both alkylated and acylated A₁₀-A₉-A₈-compounds of Formula I wherein the reduced amide bond is located between amino acid residues A₁₋ ₂, wherein A₁ is not a bond, A₂₋ ₃, A₃₋ ₄, A₄₋ ₅ or A₅₋ ₆ as described previously in Scheme B. These compounds may be deprotected according the procedure in Scheme A, step i.

Starting materials for use in Scheme E are readily availiable to one of ordinary skill in the art.

The following examples present typical syntheses as described in Scheme E. These example are understood to be illustrative only and are not intended to limit the scope of the present invention in any way.

EXAMPLE 5 Asp-Ser-Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OH]—SEQ ID NO:29.

Scheme C Step a: Boc-Ser(OBn)-Phe(OCH₃)

Mix Boc-Ser(OBn) (5.9 g, 20 mmol), Phe(OMe) hydrochloride (4.32 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Scheme C, Step b: Boc-Ser(OBn)Ψ[C(S)-NH₂]-Phe(OCH₃)

Mix Boc-Ser(OBn)-Phe(OCH₃) (456 mg, 1 mmol), 2,4-bis(phenylthio)-1,3-dithio-2,4-diphosphetane-2,4-dithione (0.45 g, 1.1 mmol) and anhydrous tetrahydrofuran (3 mL). Stir at room temperature under a nitrogen atmosphere for 8 hours. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Scheme C, Step c: Boc-Ser(OBn) [CH₂-NH₂]-Phe(OCH₃)

Dissolve Boc-Ser(OBn)Ψ[C(S)-NH₂]-Phe(OCH₃) (472 mg, 1 mmol) in a mixture of 1:1 tetrahydrofuran/methanol (10 mL). Add nickel chloride hexahydrate (NiCl₂·6H₂O) (1.9 g, 8 mmol) and cool in an ice bath. Add sodium borohydride (0.91 g, 24 mmol) and stir at room temperature under a nitrogen atmosphere for 20 minutes. Filter and evaporate the solvent in vacuo to give the title compound.

Scheme C, Step d; Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F)]-Phe(OCH₃)

Mix Boc-Ser(OBn)Ψ[CH₂-NH₂]-Phe(OCH₃) (192 mg, 0.435 mmol), 2-fluoroethyl p-toluenesulfonate (379 mg, 1.74 mmol), triethylamine (0.06 mL, 0.435 mmol) and benzene (2 mL). Heat at reflux for 7 days, occasionally adding additional 2-fluoroethyl p-toluenesulfonate and triethylamine. Cool to room temperature, wash with 1 N hydrochloric acid then saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Scheme C, Step e; Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F) ]-Phe

Dissolve Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F)]-Phe(OCH₃) (0.515 g, 1.055 mmol) in ethanol (10 mL) and add 1 N sodium hydroxide (10 mL). Stir at room temperature overnight. Dilute with water and acidify with 1 N hydrochloric acid. Extract into ethyl acetate, dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Step a; Boc-Leu[CH₂OH]

Dissolve Boc-Leu(OMe) (2.45 g, 10 mmol) in benzene (60 mL) and cool to 5° C. Add, by dropwise addition, Red-Al (20.5 mL of a 3.4 M solution in toluene, 70 mmol) and reflux for 10 minutes. Cool to room temperature, pour into ice-cold 0.5 M citric acid and adjust to pH 2.5 with citric acid. Wash with ether and adjust to pH 9 with saturated sodium hydrogen carbonate. Saturate with sodium chloride and extract with ethyl ether. Dry (MgSO₄), evaporate the solvent in vacuo and purify by silica gel chromatography to give the title compound.

Step b: Boc-Leu[CH₂OBn]

Mix Boc-Leu[CH₂OH](4.8 g, 22 mmol), benzyl chloride (2.8 g, 20 mmol), potassium carbonate (3.04 g, 22 mmol), sodium iodide (1.5 g, 10 mmol) and acetone (60 mL). Heat at reflux for 16 hours, cool to room temperature and remove the solvent in vacuo. Partition between ethyl ether and 6% sodium hydroxide. Separate the organic phase and filter off any undissolved solid from the organic phase. Dry (MgSO₄), filter and evaporate the solvent in vacuo to give the title compound.

Step c: Leu[CH₂OBn] hydrochloride

Mix Roc-Leu[CH₂OBn] (1.09 g, 3.55 mmol), 4 N hydrochloric acid in dioxane. Stir ar room temperature for 1 hour. Evaporate the solvent in vacuo to give the title compound.

Step d; Boc-Asp(O-β-Chxl)-Ser(OBn)-Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OBn]—SEQ ID NO:30.

Mix Boc-Leu (4.62 g, 20 mmol), Leu[CH₂OBn] hydrochloride (4.88 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Leu-Leu[CH₂OBn].

Mix Boc-Leu-Leu[CH₂CBn] (1.09 g, 2.60 mmol), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give Leu-Leu[CH₂OBn] hydrochloride.

Mix Boc-Gly (3.5 g, 20 mmol), Leu-Leu[CH₂OBn] hydrochloride (7.14 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSQ₄) and evaporate the solvent in vacuo to give Boc-Gly-Leu-Leu[CH₂OBn].

Mix Boc-Gly-Leu-Leu[CH₂OBn], (1.09 g, 2.29 mmol), 4 N hydrochloric acid in dioxane. Stir ar room temperature for 1 hour. Evaporate the solvent in vacuo to give Gly-Leu-Leu[CH₂OBn] hydrochloride.

Mix Boc-Val (4.34 g, 20 mmol), Gly-Leu-Leu[CH₂OBn] hydrochloride, (8.28 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Val-Gly-Leu-Leu[CH₂OBn]—SEQ ID NO:31.

Mix Boc-Val-Gly-Leu-Leu[CH₂OBn], SEQ ID NO:32, (1.09 g, 1.89), 4 N hydrochloric acid in dioxane. Stir at room temperature for 1 hour. Evaporate the solvent in vacuo to give Val-Gly-Leu-Leu[CH₂OBn] hydrochloride, SEQ ID NO:32.

Mix Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F)]-Phe (9.48 g, 20 mmol), Val-Gly-Leu-Leu[CH₂OBn] hydrochloride, SEQ ID NO:32, (10.26 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OBn], SEQ ID NO;33.

Mix Boc-Ser(OBn)Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OBn], SEQ ID NO:34, (1.09 g, 1.17 mmol), 4 N hydrochloric acid in dioxane. Stir ar room temperature for 1 hour. Evaporate the solvent in vacuo to give Ser(OBn)Ψ[CH₂-N(CH₂CH₂F) ]-Phe-Val-Gly-Leu-Leu[CH₂OBn] hydrochloride, SEQ ID NO:34.

Mix Boc-Asp(O-β-Chxl) (6.3 g, 20 mmol), Ser(OBn)Ψ[CH₂-N[CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu(CH₂OBn] hydrochloride, SEQ ID NO:34, (17.38 g, 20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) (3.83 g, 20 mmol), 1-hydroxybenzotriazole hydrate (3.06 g, 20 mmol), diisopropylethylamine (3.5 mL, 20 mmol) and methylene chloride (40 mL). Stir at room temperature under a nitrogen atmosphere until the reaction is complete. Dilute with ethyl acetate and wash with 1 N hydrochloric acid, saturated sodium hydrogen carbonate and brine. Dry (MgSO₄) and evaporate the solvent in vacuo to give the title compound.

Scheme A, step i: Asp-Ser-Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OH]—SEQ ID NO:29.

Dissolve Boc-Asp(O-β-Chxl)-Ser(OBn)-Ψ[CH₂-N(CH₂CH₂F)]-Phe-Val-Gly-Leu-Leu[CH₂OBn], SEQ ID NO:35, (113 mg, 0.1 mmol) in hydrogen fluoride and anisole. Stir at 0° C. for 1 hour. All the solvent to evaporate in vacuo to give the title compound.

The following compounds can be prepared in a similar fashion to that described above in Example 5:

Asp-Ser-PheΨ[CH₂-N(CH₂CF₂H)]-Val-β-Ala-Leu-Phe[CH₂OH]—SEQ ID NO:36; and

pyroGlu-Phe-PheΨ[CH₂-N(CH₂CH₂F)]-Gly-Leu-Met[CH₂OH]—SEQ ID NO:37.

The ability of the peptide derivatives of formula I to act as antagonists of neurokinin A can be demonstrated by, for example, the ability of such peptides to compete with iodinated neurokinin A for mammalian neurokinin A (NK2) receptors using the method of Buck, et al., Science 226: 987-989 (1984), by the ability of such compounds to stimulate or to inhibit neurokinin A-induced phosphatidylinositol turnover using the method of Bristow, et al., British J. Pharmacol. 90: 211-21 (1987), or to antagonize neurokinin A-induced smooth muscle contraction using the method of Dion, et al., Life Sciences 41: 2269-2278 (1987).

By virtue of the ability of the peptide derivatives of this invention to act as antagonists of neurokinin A, the compounds are useful as immunosuppressants and in the treatment of arthritis, asthma, pain, inflammation, tumor growth, gastrointestinal hypermotility, Huntington's disease, psychosis, neuritis, neuralgia, headache including migraine, hypertension, urinary incontinence, urticaria, carcinoid syndrome symptoms, influenza, and common cold. Effective doses, whether oral or parenteral, can be readily determined by those of ordinary skill in the art and are those doses which causes antagonism of the neurokinin A (NK2) receptor.

For example, effective doses of the peptides of this invention could be from about 0.5 μg/kg to about 500 mg/kg of the subject body weight per day. The compounds are conveniently administered in unit dosage forms containing from about 1 mg to about 500 mg of the active compound and can be administered in from one to four or more unit dosage forms per day.

Although some of the peptide derivatives may survive passage through the gut following oral administration, applicants prefer non-oral administration, for example, subcutaneous, intravenous, intramuscular or intraperitoneal; administration by depot injection; by implant preparation; or by application to the mucous membranes, such as, that of the nose, throat and bronchial tubes, for example, in an aerosol can containing a peptide derivative of this invention in a spray or dry powder form.

For parenteral administration the compounds may be administered as injectable dosages of a solution or suspension of the compound in a physiologically acceptable diluent with a pharmaceutical carrier which can be a sterile liquid such as water and oils with or without the addition of a surfactant and other pharmaceutically acceptable adjuvants. Illustrative of oils which can be employed in these preparations are those of petroleum, animal, vegetable, or synthetic origin, for example, peanut oil, soybean oil, and mineral oil. In general, water, saline, aqueous dextrose and related sugar solutions, ethanol and glycols such as propylene glycol or polyethylene glycol are preferred liquid carriers, particularly for injectable solutions.

The compounds can be administered in the form of a depot injection or implant preparation which may be formulated in such a manner as to permit a sustained release of the active ingredient. The active ingredient can be compressed into pellets or small cylinders and implanted subcutaneously or intramuscularly as depot injections or implants. Implants may employ inert materials such as biodegradable polymers or synthetic silicones, for example, Silastic, silicone rubber manufactured by the Dow-Corning Corporation.

37 10 amino acids amino acid linear peptide unknown 1 His Lys Thr Asp Ser Phe Val Gly Leu Xaa 1 5 10 7 amino acids amino acid linear peptide unknown 2 Asp Ser Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 3 Xaa Xaa Phe Val Gly Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 4 Xaa Phe Val Gly Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 5 Xaa Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 6 Asp Ser Phe Val Xaa Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 7 Xaa Phe Phe Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 8 Xaa Ser Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 9 Xaa Xaa Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 10 Xaa Xaa Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 11 Xaa Ser Phe Val Xaa Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 12 Asp Ser Xaa Xaa Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 13 Xaa Xaa Xaa Xaa Gly Leu Xaa 1 5 5 amino acids amino acid linear peptide unknown 14 Xaa Xaa Gly Leu Xaa 1 5 6 amino acids amino acid linear peptide unknown 15 Xaa Xaa Gly Leu Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 16 Xaa Xaa Xaa Gly Leu Xaa 1 5 6 amino acids amino acid linear peptide unknown 17 Xaa Xaa Xaa Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 18 Asp Ser Xaa Xaa Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 19 Asp Ser Xaa Xaa Xaa Leu Xaa 1 5 6 amino acids amino acid linear peptide unknown 20 Xaa Xaa Xaa Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 21 Asp Ser Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 22 Xaa Xaa Phe Val Gly Xaa Xaa 1 5 4 amino acids amino acid linear peptide unknown 23 Xaa Phe Val Xaa 1 4 amino acids amino acid linear peptide unknown 24 Xaa Phe Val Gly 1 6 amino acids amino acid linear peptide unknown 25 Xaa Phe Val Gly Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 26 Xaa Phe Val Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 27 Asp Ser Phe Val Xaa Xaa Xaa 1 5 6 amino acids amino acid linear peptide unknown 28 Xaa Phe Phe Gly Xaa Xaa 1 5 7 amino acids amino acid linear peptide unknown 29 Asp Xaa Xaa Val Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 30 Xaa Xaa Xaa Val Gly Leu Xaa 1 5 4 amino acids amino acid linear peptide unknown 31 Xaa Gly Leu Xaa 1 4 amino acids amino acid linear peptide unknown 32 Val Gly Leu Xaa 1 6 amino acids amino acid linear peptide unknown 33 Xaa Xaa Val Gly Leu Xaa 1 5 6 amino acids amino acid linear peptide unknown 34 Xaa Xaa Val Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 35 Xaa Xaa Xaa Val Gly Leu Xaa 1 5 7 amino acids amino acid linear peptide unknown 36 Asp Ser Xaa Xaa Xaa Leu Xaa 1 5 6 amino acids amino acid linear peptide unknown 37 Xaa Phe Xaa Xaa Leu Xaa 1 5 

What is claimed is:
 1. A peptide derivative of the formula I; X-A₁-A₂-A₃-A₄-A₅-A₆-A₇   I wherein: X is Y, wherein Y is hydrogen, an alkyl of from 1-6 carbons, an acyl group of 2-10 carbon atoms, or B₁ and B₂, wherein B₁ and B₂ are each independently selected from the group consisting of an alkyl of from 1-6 carbons and an acyl group of from 2-10 carbon atoms, with the proviso that B₁ or B₂ are not simultaneously the acyl group; A₁ is -Asp-, or a bond; A₂ is -Ser-, or PyroGlu; A₃ is -Phe-; A₄ is -Val-, or Phe; A₅ is -Gly-, or -β-Ala-; A₆ is -Leu-; and A₇ is a residue of an amino acid derivative selected from the group consisting of Methioninamide, Norleucinamide, Leucinamide, and Phenylalaninamide. wherein: the peptide derivative of Formula I is further characterized by modifying the peptide bond between the amino acid residues of A₆₋ ₇ to a modified peptide bond of

wherein Q is CH₂CF₃, CH₂CHF₂, CH₂CH₂F, or CH₂CF₂CF₃, or a pharmaceutically acceptable salt of Formula I with the proviso that when A₁-A₂ is selected to be a modified peptide bond, A₁ must be -Asp-.
 2. The peptide derivative of claim 1 wherein A₁ is -Asp-.
 3. The peptide derivative of claim 1 wherein A₂ is -Ser-.
 4. The peptide derivative of claim 1 wherein A₄ is -Val-.
 5. The peptide derivative of claim 1 wherein A₅ is -Gly-.
 6. The peptide derivative of claim 1 wherein A₇ is a residue of Leucinamide.
 7. The peptide derivative of claim 1 wherein X is hydrogen, A₁ is -Asp-, A₂ is -Ser-, A₃ is -Phe-, A₄ is -Val-, A₅ is -Gly-, A₆ is -Leu-, A₇ is the residue of Leucinamide, and Q is CH₂CF₃·SEQ ID NO:2.
 8. The peptide derivative of claim 1 wherein Q is CH₂CF₃.
 9. A pharmaceutical composition comprising a peptide derivative of formula I of claim 1 and a pharmaceutically acceptable carrier.
 10. The peptide derivative of claim 1 wherein Y is hydrogen.
 11. The peptide derivative of claim 9 wherein Y is H.
 12. A method of treating asthma in a patient in need thereof comprising administering to the patient an effective amount of a peptide derivative of claim
 1. 